Superfund Research Program
Urinary FSH Assay Developed to Assess Reproductive Health of Both Men and Women
Reproductive disorders are an increasingly common problem within the United States. Many couples ready for parenthood and with seemingly good health have been disappointed to learn that they have reproductive difficulties. Decreases in human sperm concentrations and increases in infertility of young women have been reported over the past few decades and are currently the focus of intense research and debate. Recent controversial evidence suggests that exposure to certain environmental chemicals may be contributing to the diminished reproductive capacity of adults who should be in their reproductive prime.
Adequate confirmation that reproduction is adversely affected by exposures to environmental chemicals can only be determined through methods which can evaluate both male and female fertility in toxicant exposed human populations. While many biomarker assays have been developed to assess reproductive health, most of them have focused on specific endpoints - such as infertility and early fetal loss - in women. Previous efforts have given little attention to evaluating general reproductive health in either of the sexes. Recently, researchers at the University of California at Davis developed a novel biomarker assay that is capable of assessing the general reproductive health of all adults.
The enzyme-based immunoassay works by detecting the unique urinary metabolite of follicle-stimulating hormone (FSH), a gonadotropin that is involved in the regulation of the activity of the gonads in both men and women. Intact FSH is unstable in urine and previous assays required the addition of preservative to reduce the amount of dissociation of the two subunits that make up the heterodimer. This new method measures only the beta subunit unique to FSH and provides a measure of the total amount of FSH produced.
FSH is secreted by the anterior pituitary gland and controls a number of reproductive related functions. In men the hormone promotes the development of the tubules of the testes and the differentiation of sperm. In women FSH stimulates the development of follicles in the ovary and the biosynthesis of estrogen hormones.
As a result of the production and action of FSH in both sexes, levels of FSH metabolite excreted in urine provide information regarding both gonadal and pituitary function in all adults. High levels of FSH metabolite indicate dysfunction at the gonadal level while lower than normal levels of FSH metabolite indicate diminished pituitary function. Self-collected, single-void urine samples can be used for this assessment providing for a non-invasive assay that is expected to yield a high rate of compliance when used in epidemiological studies.
The development of this new bioassay is significant because of its ability to provide a general surveillance of reproductive health for both men and women. An additional benefit is that specific information can be obtained about the target of toxicity with respect to environmental exposures. Furthermore, this enzyme based assay is relatively inexpensive and simple to carry out. Because of its simplicity, rapidity, and cost-effectiveness, this bioassay promises to be a useful screening tool of general reproductive health in epidemiological studies.
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